第5题: [单项选择]It was a very difficult task, and ______ Burrows would stop to have a smoke. A. every so often B. often so every C. so every often D. every often so 参考答案:A 答案解析:[题解] 这里是一个固定的口语表达法。词组every so often: (colloq.) often, sometimes。
第10题: [多项选择]给水硬聚氯乙烯管螺纹连接时，密封填充物宜采用( )。 A. 厚白漆、麻丝 B. 黄粉拌甘油 C. 聚四氟乙烯生料带 D. 石油密封脂 参考答案:C 答案解析:钢管螺纹连接时，常采用聚四氟乙烯生料带或厚白漆、麻丝作为密封填充物；硬聚氯乙烯管螺纹连接宜采用聚四氟乙烯生料带作为密封填充物，如使用厚白漆、麻丝时易渗漏，密封效果较差，不宜采用。黄粉拌甘油和石油密封脂
